1. Related Technical Fields
Related technical fields include navigation apparatus.
2. Description of Related Art
Conventional navigation apparatus, such as, for example, described in Japanese Unexamined Patent Application Publication No. H9-113290, display a map to a destination. The conventional navigation apparatus display information such as, for example, route information, and guide a user to a destination. The navigation apparatus use past traffic information statistics to predicted traffic conditions, such as a current or future road congestion condition.
In conventional navigation apparatus, the traffic information from outside of the vehicle is received and stored in a storage unit. When searching a guidance route, the latest traffic information and the accumulated past traffic information in the storage unit are used to search for a predicted guidance route which may be the best route to arrive at the destination in the shortest possible time.
Conventional navigation apparatus, such as, for example, described in Japanese Unexamined Patent Application Publication No. H10-019593 abstracts link travel times from traffic information received in the form of a radio beacon or optical beacon via a radio beacon device or in the form of an FM multiple broadcasting via an FM multiple receiver unit. Then the abstracted link travel times are stored in a memory. The memory stores, for example, average link travel times every 10 minutes in the last four weeks. The navigation apparatus calculates a required time to arrive at a destination based on the latest traffic information received from the radio beacon device or the FM multiple receiver. For example, if the required time is equal to or less than 1 hour, the latest traffic information may be used for a guidance route search. If the required time is longer than 1 hour, the past traffic information (link travel time information) stored in the memory may be used for searching a guidance route for excess. If the latest traffic information is not received depending on place, only the past traffic information (link travel time information) stored in the memory is used for searching the guidance route.